1. Field of the Invention
The present invention relates to cutting tools, namely inserts for machine tools, and more particularly, to small size inserts for grooving and turning.
2. Description of Related Art
The art of cutting grooves in a workpiece using a cutting tool, and particularly using an insert secured in a toolholder is well known. The use of an insert in a toolholder for turning, i.e., removing portions of material from a rotating workpiece by causing the insert to traverse along a portion of the longitudinal surface of the workpiece while the insert is sequentially advanced into the surface of the workpiece, is also known.
In one method of securing the insert during its use, particularly for grooving, cutting or threading, the insert is clamped adjacent one side of a toolholder. In this arrangement the toolholder has a nest or pocket formed by a bottom wall and a side wall, and the insert is held in position by a top clamp. Such an arrangement is illustrated in U.S. Pat. No. 3,754,309, issued to Jones et al. on Aug. 28, 1973.
Turning, for example in a lathe, advantageously is performed by traversing and removing material from the workpiece in both longitudinal directions. However, attempts to use the same insert within a holder for both grooving and turning, especially during turning in both directions, presents problems in securely and accurately maintaining the insert in position during these operations. In particular, during turning, and most especially upon the workpiece being traversed in the direction outwardly from that side of the holder to which the insert is clamped, the outward end of the insert held by a clamp to the toolholder tends to slip or rotate sideways due to the lateral force of the workpiece on the outward end of the insert. This is particularly the case where the bottom insert supporting surface of the holder is planar and perpendicular to the sides as in U.S. Pat. No. 3,754,309. Even where the bottom insert supporting surface of the holder is not planar, but is angled as in U.S. Pat. No. 6,000,885, issued to Erickson on Dec. 14, 1999, the insert tends to slip or rotate from the holder.
Attempts have been made to overcome the tendency of the insert to slip or rotate in the holder due to lateral force on the insert, for example by forming a diagonal notch in the insert and angling the clamp element to engage the notch and by forming recessed angled portions in the top and/or bottom surfaces of the insert, as in U.S. Pat. Nos. 3,754,309 and 6,000,885. However, such attempts have generally been imperfect to counter the force exerted oh the insert as explained in U.S. Pat. No. 6,000,885. Furthermore, the attempts to date have not been applicable to small-size inserts. Small-size inserts are inserts having grooving widths in the range of from about 0.004 inch to about 0.150 inch and a body width in the range of 0.15 inch, for example 0.155 inch. Due to the small size of these inserts, it is impractical to attempt to form diagonal notches and recessed portions in the shank portion of the insert, particularly where the insert is formed of a material such as carbide or of hardened steel.
It is of further utility for inserts to have the capability of being interchangeably mounted in parallel to the longitudinal axis to one side of a toolholder or the other, that is xe2x80x9cright handxe2x80x9d or xe2x80x9cleft handxe2x80x9d, or facing to the right or to the left when installed on a toolholder perpendicular to the longitudinal axis of the toolholder for such operations as internal boring.
It is further advantageous in many applications for inserts to have dual cutting regions or heads, for example, so that the insert life can be extended by employing the second cutting head when the first head becomes dull or chipped through use. With some dual head insert configurations, the insert must be inverted as well as reversed in order to employ the second head, as in U.S. Pat. No. 4,669,924, issued to Benson on Jun. 2, 1987, and in U.S. Pat. No. 6,000,885, noted above.
Thus, there exists a need for small-sized inserts which are adapted to resist forces exerted on the insert, particularly during turning.
There is a further existing need for small size inserts which can be mounted on either the right-hand or the left-hand portions of a toolholder to facilitate use of existing toolholders which may be mounted to the machine tool, for particular operations, without the need for changing to a toolholder of the alternate hand configuration, e.g., right-hand to left-hand toolholders. A further need is for inserts with dual cutting heads which can be employed without inverting the insert, thus facilitating mounting the insert to a toolholder. A still further need is for inserts with provision for preventing rearward movement of the insert with respect to the machine tool when in use. Unwanted rearward movement of the insert in the toolholder with respect to the machine tool is undesirable as it may cause the depth of the cut or grooving and/or turning to be in error, and often causes downtime due to the necessity to remount the insert and perhaps require recalibration of the tool to ensure its accurate operation.
It is an object of the present invention to provide a small-size insert which is securely held within a holder even when encountering lateral forces which tend to move the insert out of position with respect to the holder.
It is another object of the invention to provide a small-size insert which does not require recesses or notches in order to be securely held in position during grooving and turning.
It is still another object of this invention to provide a small size insert which can be securely held in position during grooving, cutting, as well as during turning in both directions along the workpiece.
A further object of this invention is to provide a small-size insert, and a blank therefore which can be formed into an insert, adapted for either right-hand or left-hand mounting to a toolholder.
Another further object of this invention is to provide a small-size insert with dual cutting heads or ends which is adapted for either right-hand or left-hand mounting to a toolholder without the need for inverting the insert for alternate mounting to the toolholder.
Still another further object of this invention is to provide an insert with provision for preventing rearward movement of the insert with respect to the machine tool when in use.
These and other objects and advantages of the present invention will be apparent from the following description.
In accordance with one aspect of the present invention an apparatus is provided which is adapted for use with a machine tool for grooving and turning. The apparatus comprises a body having first and second sides which are generally parallel and opposing each other, first and second ends, and top and bottom surfaces. The sides and top and bottom surfaces of the apparatus extend from adjacent the first end to the second end. Thus, the first end extends longitudinally beyond the sides and top and bottom surfaces of the body. The top surface has at least a portion thereof extending from adjacent the first end to the second end and is inclined downwardly from the perpendicular of the top end of the first side to the second side. The bottom surface has at least a portion thereof extending from at least adjacent the first end to the second end and is inclined upwardly from the perpendicular of the bottom edge of the first side to the second side. In the present invention, the first end may have generally parallel walls and may have a polygonal cross-section, and is adapted to be formed into an insert portion, for example by grinding into a desired shape of a cutting tool and/or grooving tool end. Alternatively, the first end may be a cutting tool and/or grooving tool end.
The apparatus of the present invention is intended to be utilized with a toolholder having a nest or pocket formed having an inclined bottom wall which is adapted to support the bottom surface of the apparatus of the invention. The apparatus of the present invention is intended to be securely retained in the nest or pocket of the toolholder by means of a lever-type clamp which is secured to the toolholder by means of a fastener, such as a machine screw, and exerts a downward force on the body of the apparatus. The clamp with which the apparatus of the present invention is held in the nest or pocket of the toolholder includes an inclined surface or angled end which cooperates with the inclined portion of the top surface of the apparatus to securely hold the apparatus in position in the toolholder.
Preferably, in this aspect of the present invention, the top surface of the apparatus has a second portion extending from adjacent the first end to the second end of the apparatus perpendicularly from the top edge of the first side toward the second side. In such preferred arrangement, the inclined portion of the top surface may extend downwardly from the second portion to the second side at an acute angle with respect to second portion of the top surface. In this manner, the entire top surface need not be inclined, reducing the possibility that a burr or high spot on the nest or pocket bottom wall or on the apparatus body bottom surface may prevent the apparatus from firmly and securely being supported by the nest or pocket bottom wall.
Similarly, the bottom surface of the apparatus may have a second portion extending from adjacent the first end to the second end perpendicularly from the bottom edge of the first side toward the second side. In this preferred arrangement, the inclined portion of the bottom surface may extend upwardly from the second portion to the second side at an acute angle with respect to second portion of said bottom surface. As the lever-type clamp only contacts a portion of the top surface of the apparatus, only the corresponding portion of the top surface of the apparatus need be inclined. In this preferred arrangement, the apparatus of the present invention is securely held in position in the toolholder even upon encountering lateral forces during grooving, as heretofore explained.
In accordance with another aspect of the present invention, the apparatus adapted for use with a machine tool for grooving and turning comprises a head substantially identical to the first end described in connection with the first aspect of the invention described above, and a body integral with the head. As in the case of the first aspect of the invention, the apparatus may be a blank, that is a tool with a head which is unformed, but is capable of being formed into a cutting, grooving and/or turning head, for example, by grinding, or may be an insert with a finished head for cutting, grooving and/or turning, or for other machine tool operation. The head in this aspect has a rear end and the body extends generally longitudinally, i.e., rearwardly, from the rear end of the head. The body has first and second sides which are generally parallel to and opposing each and extends from the rear end of the head to the distal end of the body which corresponds to the second end of the body in the first aspect described above
The body of the apparatus in this aspect of the invention includes top and bottom surfaces which extend from the rear end of the head to the distal end and from the first side to the second side. The top surface has a first portion intersecting with and extending from the rear end of the head to the distal end of the body and is inclined upwardly from the first side of the body. The top surface has a second portion intersecting with and extending from the rear end of the head to the distal end of the body and is inclined upwardly from the second side of the body. The inclined first and second portions of the top surface of the body desirably cooperates with a lever-type clamp to secure the apparatus in the nest or pocket of a toolholder as heretofore described in connection with the first aspect of the invention. The advantage of having first and second inclined top surface portions is that the apparatus can be oriented in either a right-hand or left-hand toolholder, which are known to the art, and clamped therein with the clamp exerting the clamping force on the corresponding inclined top surface portion.
The top surface of the body of the apparatus of this aspect of the invention may include a third portion extending from the rear end of the head to the distal end of the body and from the first top surface portion to the second top surface portion. Preferably, the third top surface portion extends substantially perpendicularly from the plane of at least one of the sides of the body. Also, preferably the first and second top surface portions extend at acute angles, respectively, from the third portion downwardly to the first and second sides of the body.
The bottom surface also desirably has first and second surface portions each intersecting with and extending from the rear end of the head to the distal end of the body and inclined downwardly from respective first and second sides of the body. The bottom surface of the body of the apparatus with its first and second inclined portions forms a shallow V-shape extending in the longitudinal direction, and is adapted to fit and be seated into a nest or pocket of a toolholder with an inclined bottom surface as heretofore described. The first and second inclined bottom portions of the body of the apparatus in this aspect of the invention provides the apparatus with the capability to be secured within the nest or pocket of right-hand or left-hand toolholders with inclined bottom surfaces, with the corresponding bottom surface portion resting on the inclined bottom surface of the pocket of either type of holder.
Further in this aspect of the invention, the rear end of the head of the apparatus has rearwardly facing portions or triangular corners below its intersections with the downwardly inclined first and second bottom surface portions of the body of the apparatus. These rearwardly facing portions of the rear end of the head are adapted to each or both serving as stops of the apparatus which may bear against a surface of the toolholder to prevent rearward movement of the apparatus with respect to the machine tool when in use. The rear end of the head of the apparatus may also have rearwardly facing portions or triangular corners above its intersections with the upwardly inclined first and second portions of the top surface of the body. These portions or corners can also serve as stops to prevent rearward movement of the apparatus with respect to the machine tool when in use. As in the case of the lower rearward facing portions or corners of the rear end, either upper portion or both may bear against a surface of the toolholder in preventing rearward movement. By xe2x80x9crearward movementxe2x80x9d as described herein, the movement which is sought to be prevented is rearward movement of the apparatus, which in the case of the apparatus mounted transversely to the toolholder similar to the transverse mounting arrangement of an insert and support shown in FIG. 6 of Smith et al., U.S. Pat. No. 5,638,728, issued Jun. 17, 1997, as compared to the longitudinal mounting of an insert and support shown in FIG. 1 of that patent. It is further contemplated that both lower rear end rearward facing portions or corners described herein may serve as stops against rearward movement for balanced preventive force, or the upper portions or corners or both top and bottom rearward facing portions or corners may serve as stops against rearward movement of the apparatus.
In still another aspect of this invention, the apparatus comprises a second head extending from the distal end of the body of the apparatus. The second head may be the mirror image of the head described above. The advantage of having apparatus with a second head will be apparent to those skilled in the art, particularly for extending the life of the apparatus when formed into an insert or as an insert if previously so formed, by employing the second head when the cutting surface of surfaces of the first head becomes dull or otherwise unusable as a practical matter through use.